05000366/LER-1981-078-03, /03L-0:on 810820,reactor Core Isolation Cooling Flow Controller Demand Was at Less than 100% While in Either Auto or Manual.Caused by Faulty Resistor in Ramp Generator. Units Replaced

/03L-0:on 810820,reactor Core Isolation Cooling Flow Controller Demand Was at Less than 100% While in Either Auto or Manual.Caused by Faulty Resistor in Ramp Generator. Units Replaced

ML20010G738
Person / Time
Site:	Hatch
Issue date:	09/10/1981
From:	Coggin C GEORGIA POWER CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML20010G735	List: 05000366/LER-1981-078, Forwards LER 81-078/03L-0 05000366/LER-1981-078-03, /03L-0:on 810820,reactor Core Isolation Cooling Flow Controller Demand Was at Less than 100% While in Either Auto or Manual.Caused by Faulty Resistor in Ramp Generator. Units Replaced
References
LER-81-078-03L-01, LER-81-78-3L-1, NUDOCS 8109220468
Download: ML20010G738 (2)

LER-1981-078, /03L-0:on 810820,reactor Core Isolation Cooling Flow Controller Demand Was at Less than 100% While in Either Auto or Manual.Caused by Faulty Resistor in Ramp Generator. Units Replaced

Event date:
Report date:
3661981078R03 - NRC Website

text

e U.S. NUCLEAR REGULATORY COMMISSION NRC FORM 366 LICENSEE EVENT REPORT

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60 61 DOCKET NUMBER 68 69 EVENT DATE 74 75 REPORT OATE 80 EVENT DESCRIPTION AND PROBABLE CONSEQUENCES h I O 12 I I On 8-20-81. with Unit 2 at steadv state 88.3*L thermn1 nntaor - tah i l o t-h o I

10 l a l l "ECCS Status Check" was being performed and on 8-21-81 with Unit 2 at I

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1014i i steady state 86.9% thermal power, an operator noticed that the'RCIC flowl Icontroller demand was at 4 100% while in either auto or in manual.

RCICI O s

!O is l lwas declared inop and per Tech Spec 3.7.3,HPCI was operable.

There werel 1017 l [ no effects upon public health and safety due to this event.

This is a I

IOisiirepetitive occurrence (Ref. LER 50-366/1981-010).

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40 41 42 43 44 47 CAUSE DESCRIPTION AND CORRECTIVE ACTIONS h g lThe cause was due to ai fa61ty resistor in the RCIC ramp generator.

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,, jii icaused self sync control module to fail on 8-20-81, and the ramn eenera-1 i,i,,i tor to fail on 8-21-81.

Thefunite were replaced on those respective I

i,,.,ijdates and RCIC was proven operable both times.

The unit is now in full I i,giicompliance with the requirements and no further reporting is required.

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LER #: 366/1981-078 Licensee:

Georgia Power-Company Facility Name:

Edwin I. Hatch j-Docket #:- 50-366

Narrative

Report 3

[

for LER 50-366/1981-078 i

. On.8-20-81, with Unit 2 at steady _stete 88.3% thermal' power,;

the "ECCS Status Check" (HNP-2-1119) was being performed.

It was observed by the shift.perrannel that 'the RCIC flow controller was not indicating _ greater than :100%. demand while.

the RCIC system was. in-standby. condition.

The' controller was F

placed in manual and the 1 demand: dropped ' further.

The RCIC system was declared inoperable (Ref: Deviation-2-81-138) and per Tech Spec 3.7.3, HPCI. was operable.. No 'significant event occurred.

i, Upon investigation _it was dete'rmined that the self sync.

I control.. module. output circuit was broken.

The module was 1

i replaced and 'the system was proven operable per HNP-2-3405 "RCIC Pump Operability".

i La 8-21-81, with Unit 2 at steady state 86.9% thermal power, a control room operator observed.that the RCIC. flow controller, while RCIC vas in standby mode, drift'ed down from. greater than 100% demand to less than 70% demand.

Placing the controller in manual, the demand ~ drif ted further downward.

The RCIC i

system was declared inoperable -(Ref: Deviati~on 2-81-139) and per Tech : Spec 3.7.3, HPCI was operable.

No significant event accurred.

I Upon investigation it was discovered that-a. resistor in the RCIC ramp generator circuitry was defective and was heating' th'e circuitry to a point of failure.

As the resistor _ cooled, the ' circuitry became operable.

This defective resistor was-

+

the cause of the self sync' module failing.on 8-20-81.-

The ramp generator we:: ' replaced, i

' This is a-repetitive event (Ref: LER 50-366/1981-10) and there l

were no effects upon public - ~ health and safety-due to this

. event.

The unit is now in full compliance with

'the requirements and no-further reporting is required.

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